marss 0.0.3

Mars celestial simulation crate for the MilkyWay SolarSystem workspace
Documentation 
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#[derive(Debug, Clone)]
pub struct Vertex {
    pub position: [f64; 3],
    pub normal: [f64; 3],
    pub uv: [f64; 2],
    pub tangent: [f64; 4],
}

pub struct TerrainMesh {
    pub vertices: Vec<Vertex>,
    pub indices: Vec<u32>,
}

impl TerrainMesh {
    pub fn from_region(
        lat_min: f64,
        lat_max: f64,
        lon_min: f64,
        lon_max: f64,
        subdivisions: usize,
    ) -> Self {
        let n = subdivisions + 1;
        let mut vertices = Vec::with_capacity(n * n);
        let mut indices = Vec::with_capacity(subdivisions * subdivisions * 6);

        for j in 0..n {
            let v = j as f64 / subdivisions as f64;
            let lat = lat_min + v * (lat_max - lat_min);
            let lat_rad = lat.to_radians();

            for i in 0..n {
                let u = i as f64 / subdivisions as f64;
                let lon = lon_min + u * (lon_max - lon_min);
                let lon_rad = lon.to_radians();

                let r = crate::MARS_RADIUS + super::heightmap::mars_elevation(lat, lon);

                let (sin_lat, cos_lat) = lat_rad.sin_cos();
                let (sin_lon, cos_lon) = lon_rad.sin_cos();

                let px = r * cos_lat * cos_lon;
                let py = r * cos_lat * sin_lon;
                let pz = r * sin_lat;

                let nx = cos_lat * cos_lon;
                let ny = cos_lat * sin_lon;
                let nz = sin_lat;

                let tx = -sin_lon;
                let ty = cos_lon;

                vertices.push(Vertex {
                    position: [px, py, pz],
                    normal: [nx, ny, nz],
                    uv: [u, v],
                    tangent: [tx, ty, 0.0, 1.0],
                });
            }
        }

        for j in 0..subdivisions {
            for i in 0..subdivisions {
                let tl = (j * n + i) as u32;
                let tr = tl + 1;
                let bl = ((j + 1) * n + i) as u32;
                let br = bl + 1;
                indices.extend_from_slice(&[tl, bl, tr, tr, bl, br]);
            }
        }

        Self { vertices, indices }
    }

    pub fn vertex_count(&self) -> usize {
        self.vertices.len()
    }
    pub fn triangle_count(&self) -> usize {
        self.indices.len() / 3
    }
}